1. Field of the Invention
This invention relates to a method for generating an X-ray with high brightness and to an apparatus for generating the same X-ray.
2. Description of the Related Art
In the X-ray diffraction measurement or the like, it is often required that an X-ray with an intensity as high as possible is irradiated onto a sample so as to realize the X-ray diffraction measurement. As such an X-ray generating apparatus as being employed for the X-ray diffraction measurement, an X-ray generating apparatus of rotating anticathode target is conventionally well known.
The rotating anticathode X-ray generating apparatus is configured such that an electron beam is irradiated onto the outer surface of the columnar anticathode target while the columnar anticathode target is rotated under the condition that a cooling medium is flowed in the columnar anticathode target. The rotating anticathode X-ray generating apparatus has an extreme high cooling efficiency because the irradiating portion of the electron beam is varied with time in comparison with an X-ray generating apparatus of stationary target. Therefore, an electron beam can be irradiated onto the anticathode target under the condition of large current to generate an X-ray with high intensity (high brightness).
In this case, however, the intensity of the electron beam to be irradiated per unit area on the target is increased, causing the partial melting for the target and the splashing of the melted target. Therefore, theoretically, the brightness of the x-ray can be increased based on the aforementioned relation, but practically, is restrictive due to the melting point of the target.
In view of the aforementioned problem, such an attempt is made in Reference 1 as irradiating an electron beam onto the inner side of the cylindrical portion of a rotating anticathode X-ray generating apparatus so as to heat the irradiating portion to a temperature equal to or near the melting point of the anticathode target and generate an X-ray with high brightness. In this case, since the irradiating portion of the electron beam is heated to a temperature around the melting point of the rotating anticathode target, the electron beam irradiating portion is at least partially melted. However, since the electron beam irradiating portion is kept against the cylindrical portion by the centrifugal force generated by the rotation of the rotating anticathode target, the partially melted portion of the target, originated from the electron beam irradiation, cannot be splashed outward from the cylindrical portion.
According to Reference 1, therefore, since the intensity of the electron beam to be irradiated can be increased per unit area of the target under the condition that the melting and splashing of the rotating anticathode target are prevented, an X-ray with an relatively higher brightness can be obtained as compared with a conventional one.
[Reference 1] JP-A 2004-172135
In view of high resolution analysis and examination, however, it is required to realize the X-ray with higher brightness. Moreover, it is desired to realize the X-ray with higher brightness under the condition of low electric power.